Junction having improved formation collapse resistance and method

ABSTRACT

A junction includes a borehole casing having a window therein; a diverter disposed within the casing and aligned and oriented with the window, the diverter having at least one profile along a longitudinal edge thereof; and a hanger assembly having a window therein, the window having an edge receivable by the at least one profile, the profile supporting the hanger assembly and method.

BACKGROUND

In the hydrocarbon recovery industry, multilateral wells have become more and more used over the last decade or so. In each case of a lateral borehole extending from a primary borehole or from another lateral borehole, a natural junction is necessarily created in the formation. In the vernacular of the hydrocarbon recovery industry, the term “junction” usually refers to the man-made part of the well structure that is built into the natural junction to convey the targeted hydrocarbon to the surface. In some cases, the junction is intended to be a pressure competent structure, while in others there is no reason for the junction to contain pressure. In either type, there is an interest in the junction to be capable of withstanding formation collapse so that the well will function for its intended purpose, regardless of the collapse. Different materials have been used with inherent expense and thicker materials have been used, again with inherent expense. While such configurations can be effective in alleviating the effects of formation collapse to some extent, the added expense is undesirable and alternate configurations and methods are always well received by the art.

SUMMARY

A junction includes a diverter having profiled longitudinal edges; and a hanger assembly configured to engage the profiled longitudinal edges.

A method for improving collapse resistance of a junction includes disposing a diverter having a profiled longitudinal edge in a borehole at an intersection with a lateral borehole; and engaging a hanger assembly with the profiled longitudinal edge.

A junction includes a borehole casing having a window therein; a diverter disposed within the casing and aligned and oriented with the window, the diverter having at least one profile along a longitudinal edge thereof; and a hanger assembly having a window therein, the window having an edge receivable by the at least one profile, the profile supporting the hanger assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings wherein like elements are numbered alike in the several Figures:

FIG. 1 is a perspective view of a first embodiment of the junction configuration as disclosed herein;

FIG. 2 is a cross section view of FIG. 1 taken along section line 2-2;

FIG. 3 is a perspective view of a second embodiment of the junction configuration as disclosed herein;

FIG. 4 is a cross section view of FIG. 3 taken along section line 4-4;

FIG. 5 is a perspective view of a third embodiment of the junction configuration as disclosed herein;

FIG. 6 is a cross section view of FIG. 5 taken along section line 6-6.

DETAILED DESCRIPTION

Initially, it will be helpful to point out that a part of the teaching hereof is to provide for support of a hanger assembly by a seal bore diverter instead of by a casing structure through which the hanger extends. Such a configuration allows one to take advantage of the excess strength that exists in the invariably thicker material of the seal bore diverter. Such support can be accomplished in several ways, the following embodiments being representative but not limiting.

Referring to FIGS. 1 and 2, a junction 10 is illustrated in perspective view. A casing 12 of a primary bore, whether that actually is a mother bore to the surface, or another lateral, is shown with a seal bore diverter 14 therein. One of ordinary skill in the art will be familiar with a seal bore diverter but not with the profile illustrated thereon in FIG. 1. The seal bore diverter 14 includes a diverter face 16 bounded on each longitudinal edge thereof by a recess 18, 20. Each recess as illustrated comprises two surfaces. One of the surfaces is a radial support surface 22 and the other is a hoop support surface 24. Surfaces 22 and 24 intersect at an acute angle 26 in one embodiment, although it is possible for the intersection to occur at an obtuse angle with consequent reduction in hoop support. In the illustration of FIGS. 1 and 2, the angle 26 is about 30 degrees to about 89.9 degrees.

The surfaces 22 and 24 are dimensioned to approximately the thickness of a hanger assembly 26, intended to be engaged therewith. This can be appreciated most easily by viewing FIG. 2. It is to be understood, however, that it is not required that the dimensions of surfaces 22 and 24 be exactly the same as a surface 30 of hanger assembly 26 but that the dimensions of surfaces 22 and 24 may be somewhat larger or somewhat smaller than surface 30 without significant change in function of the configuration.

The dimensions of surfaces 22 and 24 are a product of the annular dimension of the sealbore diverter 14 at the cross sections point at which a sectional view is taken. In the FIG. 2 view, however, it is evident that the dimension of surfaces 22 and 24 provides significant radial support to the hanger assembly 26 relative to what the casing itself might provide simply because of the much greater surface area available on surfaces 22 and 24. Prior art arrangements are provided support only by the casing 12 and only by happenstance, as a direct teaching for support of the junction in such manner is not to be found in the prior art.

With the arrangement as illustrated in FIGS. 1 and 2, a significant formation collapse resistance is achieved by providing both a much greater surface area for radial support and a hoop support that has not been provided in the past. Crush resistance is significantly increased both because the hanger assembly 26 cannot close at its own window due to surfaces 22 and 24 and because a greater percentage of the hanger assembly 26 is radially supported. The recesses 18 and 20 may be provided by machining, or may be molded in, etc.

In another embodiment, referring to FIGS. 3 and 4, each longitudinal edge 40 of the seal bore diverter 14, is configured as a flat face 42, so that hoop stress in the hanger assembly 26 is supported during the application of formation collapse pressure on the hanger assembly 26. It is to be appreciated that in this embodiment, the window 44 in the hanger assembly 26 is milled differently than is usually the case in the art. Rather, as can be ascertained from a view of FIG. 4, window edge surfaces 46 are about ninety degrees from an angle such as that seen in FIGS. 1 and 2. The edges 46 are thus well supported by flat faces 42. This particular embodiment boasts very easy machining to create but as will be appreciated by an attentive reader, the hoop strength improvement of this embodiment is less than that attained in the embodiment of FIGS. 1 and 2.

In yet another alternate embodiment, referring to FIGS. 5 and 6, the seal bore diverter 14 is differently configured to have a scooped ramp 50 on both longitudinal sides of the diverter face 16. In this embodiment, a relatively large surface area of the hanger assembly 26 is supported by the diverter 14 by each of the ramps 50. This provides added collapse resistance, by simple spreading of the load and is otherwise a simple modification to make to a diverter 14 and thus inexpensive.

While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation. 

1. A junction comprising: a diverter having profiled longitudinal edges; and a hanger assembly configured to engage the profiled longitudinal edges.
 2. The junction as claimed in claim 1 wherein the profiled edges comprise a radial support surface.
 3. The junction as claimed in claim 1 wherein the profiled edges comprise a hoop support surface.
 4. The junction as claimed in claim 1 wherein the profiled edges each comprise a recess.
 5. The junction as claimed in claim 1 wherein the profiled edges comprise a ramped surface.
 6. The junction as claimed in claim 1 wherein the profiled edges comprise a flat face.
 7. The junction as claimed in claim 1 wherein the profiled edges comprise at least a radial support surface and a hoop support surface.
 8. The junction as claimed in claim 7 wherein the radial and hoop support surfaces intersect one another.
 9. The junction as claimed in claim 8 wherein the intersection is at an acute angle.
 10. The junction as claimed in claim 8 wherein the intersection is at an obtuse angle.
 11. The junction as claimed in claim 9 wherein the acute angle is about 30 degrees to about 89.9 degrees.
 12. A method for improving collapse resistance of a junction comprising: disposing a diverter having a profiled longitudinal edge in a borehole at an intersection with a lateral borehole; and engaging a hanger assembly with the profiled longitudinal edge.
 13. A junction comprising: a borehole casing having a window therein; a diverter disposed within the casing and aligned and oriented with the window, the diverter having at least one profile along a longitudinal edge thereof, and a hanger assembly having a window therein, the window having an edge receivable by the at least one profile, the profile supporting the hanger assembly.
 14. The junction as claimed in claim 13 wherein the supporting is radial.
 15. The junction as claimed in claim 13 wherein the supporting is in hoop. 